Seems to me the cheapest solution is to glue old playing cards to the tire rims so that they smack something as the wheel turns. A variation of this worked on my bike when I was a kid. ...although I would still run into people occasionally ;-)

Bert, you're absolutely correct. And re-reading the NHTSA reduction estimate quote, they see the reduction over the life of the various models... which ends up being a very small number on a year-by-year basis.